1. Field of the invention
The present invention relates to an interchangeable lens camera and more precisely it relates to a mount apparatus of an interchangeable lens camera in which electrical contacts for photographing signals and/or for power supply are provided on mount surfaces of a camera body and an interchangeable lens which is to be detachably attached to the camera body.
2. Description of Related Art
In an interchangeable lens camera, a mount lock member is provided on a body mount to be disengageably engaged in a lock hole of a lens mount, so that the mount lock member is retracted from the body mount by pushing a mount lock releasing member to release the lock. In an interchangeable lens camera which has a driving motor for an automatic focusing device (on the interchangeable lens side), and a diaphragm driving device, etc. on the camera body, a joint shaft (drive shaft) which functionally connects the driving motor and a driving mechanism on the interchangeable lens side is additionally provided on the body mount. The joint shaft which is continuously biased into a projected position is retractable from the body mount surface. In this kind of interchangeable lens camera, it is necessary to provide an electrical connecting means for transmitting various photographing information between the camera body and the interchangeable lens or for supplying the electrical power from an electrical power source provided in the camera body to the driving motor. There are various known electrical connecting means. For example, as disclosed in PCT Application No. JP87/00067 and U.S. Pat. No. 4,564,265, it is known to provide contact members on the body mount and the lens mount so as to establish an electrical connection therebetween when the mounts are connected to each other. However, in this type of connection in which the contact members are provided on the mounts, a transmission loss tends to occur due to the contact resistance therebetween. To avoid this, the contact surfaces are usually subject to a surface treatment for reducing the contact resistance. However, the solution by the surface treatment has a drawback because the surface treatment layers can be easily stripped or separated from the body of the associated contact members due to a repeated rubbing between the mount surfaces upon mounting and dismounting the lens mount to and from the body mount, thus resulting in wearing of the surface treatment layers or poor contact between the contact members.